The most valuable fish in the sea is the tuna. Every year in early summer, they swim in from the Atlantic to spawn. They are immense, some as much as twelve feet long. Because of the shape of the coastline and the topography of the sea floor, in some places they have to swim along a restricted and predictable route - and there the people wait for them. Nets hanging from floats are stretched diagonally across the migration path. The fish swim along the face of them, seeking a way past until they enter a corridor that not only has an end wall, but a floor of netting. Once they have started down it, the fishermen pull up the end of the floor and the fish are trapped. The net is pulled in, forcing the fish closer to the surface. As they thrash about in panic, the fish so exhaust themselves that some are already close to death. One single chamber may have trapped a hundred of these giant fish. When the last have been collected, the netting floor is dropped again to wait for the next shoal, which may arrive within a few hours.